Generally, an ACB (air circuit breaker) includes a stationary contactor and a movable contactor movable to a connected position for closing a conducted circuit by contacting the stationary contactor and to an interruption (trip) position for opening the conducted circuit by being separated from the stationary contactor, and allow the stationary contactor and the movable contactor to be contacted at all times for flowing the current, but when an abnormal over-current (a large current caused by i.e., short circuit and ground fault) generated at an electric circuit such as a power transmission/distribution line and private power transforming facilities occurs, the movable contactor is swiftly separated from the stationary contactor to interrupt the current from flowing to thereby protect load units such as a motor and a transformer and an electric line against an abnormal current. The ACB also exposes the stationary and movable contactors to pull in the compressed air and to distinguish the arc generated during the occurrence of abnormal current.
As noted above, the ACB is utilized for connecting a high-voltage current to or interrupting the current from a power station or distributing station, and is mounted, if necessary, with an actuator for swiftly interrupting or separating a contact point between the stationary contactor and the movable contactor. The driving method of the actuator is largely classified into a manual manipulation method, a solenoid manipulation method and an electric spring manipulation method.
In the ACB of the electric spring manipulation method, an interruption spring is elastically connected to one side of a cam axle mounted with a charging cam connected to a link connected to a movable contactor, and a manual charging device rotating the cam axle using a manual lever or an electric charging device using a motor is connected to the cam axle. The cam axle is rotated while a rotation moment-added main energy is maximally accumulated in the interruption spring using the charging device. If necessary, a lock is released to rotate the cam axle using the accumulated energy of the interruption spring and sequentially-meshed link separates the movable contactor from the stationary contactor to interrupt the current.
FIG. 1 is a perspective view illustrating configuration of a typical ACB and FIGS. 2a, 2b and 2c are schematic views sequentially illustrating an operational state of an actuator mechanism.
Referring to FIGS. 1, 2a, 2b and 2c, the typical ACB includes a connection spring (11) selectively separating or connecting a contact point between a stationary contactor (3) and a movable contactor (5) for opening and closing a conducted circuit, an actuator mechanism (1) including a linkage (15), an interruption spring (21) and a cam axle (30), a motor (50) rotating the cam axle (30), and a charging device (40) including a decelerating gear assembly (60) and an output gear (70).
Now, referring to FIGS. 2a, 2b and 2c, the actuator mechanism (10) of the typical ACB will be described. FIG. 2a illustrates an initial state of the actuator mechanism (1) where the contact point between the stationary contactor (3) and the movable contactor (5) are opened.
Thereafter, the cam axle (30) is rotated by the driving motor (50) or a charging handle (not shown), and a driver lever (16) is rotated by rotation of a charging cam (12) meshed with the cam axle to compress the connection spring (11) to be in a state illustrated in FIG. 2b, i.e., in the state of being charged. The changing cam (12) accumulated by the connection spring (11) maintains an equilibrium of force due to an ON lever (14) contacting a connection latch (13). An ON coupling (17) contacting a connection solenoid (not shown) is in a position capable of rotating the ON lever (14).
Then, when a user presses a connection button, or rotates the ON lever (14) by allowing the connection solenoid to move the ON coupling (17) downward, the connection latch (13) releases the charging cam (12) to allow the accumulated force of the connection spring (11) to be transmitted to the linkage (15) via a driver lever (16). An open/close axis (10) is rotated clockwise to allow contact points of the stationary contactor (3) and the movable contactor (5) to be contacted therebetween via an open/close lever (20) rotating in conjunction with the open/close axis (10) and to elongate the interruption spring (21), the state of which is illustrated in FIG. 2c. The state of the contact points between the stationary contactor (3) and the movable contactor (5) being contacted, i.e., the equilibrium of force where the air breaker is connected, is maintained by an open lever (23) via the linkage (15) and an open latch (22).
Thereafter, when a user presses an interruption button (now shown) by detecting an occurrence of over-current caused by failure at an electric line, or the open lever (23) is rotated by operation of the interruption solenoid (now shown), the open latch (22) is rotated to release the linkage (15) toggled by the connection operation and to rotate the open/close axis (10) according to force elongated by the interruption spring (21), such that the contact point of the stationary contactor (3) and the movable contactor (5) is separated to form a state illustrated in FIG. 2a. 
Meanwhile, FIG. 3 is a cut-away view of a typical driving motor of FIG. 1. Now, the motor using a connection spring charging device of a typical ACB will be described with reference to the accompanying drawings.
As illustrated in FIG. 3, the typical motor (50) includes a shaft (130) rotatably mounted inside a first frame and a second frame (110, 120) via a bearing (135) tight fitted into the first and second frame (110, 120) made of aluminum, a commutator (140) pressure-fitted into one side of the shaft (130), a stator winding (170) rotating the shaft (130), a brush holder (160) inserted into the first frame (110), a brush (150) contacting the commutator (140) by being inserted into the brush holder (160) so as to be elastically supported by a spring (not shown), and a brush holder isolator (180) isolating the brush holder (160) from the first frame (110).
However, the typical motor (50) thus constructed suffers from the following problems.
First, an electric wiring connected to the stator winging (170) at one side of the brush holder (160) is soldered for connecting the brush holder (160) and the stator winding (170). The problem is that it is very difficult to solder, and the motor (50) may not be properly driven due to improper soldering caused by erroneous work by a worker and the interruption operation of the ACB may not properly conducted.
Besides, the first and second frames (110, 120) are made of aluminum by die-casing method to cause a difficulty in insertion work of a bearing that is tightly fitted into the first and second frames (110, 120) for a smooth rotation of the shaft (130). Still another problem is that the manufacturing cost of the ACB increases, because a brush holder isolator (180) isolating the brush holder (160) from the first frame (110) has to be additionally mounted for isolation from the brush holder (160).